1. Vaccine policy changes and epidemiology ofpoliomyelitis in the United States;Alexander;JAMA,2004
2. Circulatingvaccine-derived polioviruses: current state of knowledge;Kew;Bull WHO,2004
3. WHO Polio Unit. “One million vaccinators, 80 million children, 23 countries: Africa launcheslargest public health event in history”. Press release, 8 October 2004.
4. Global polio eradication initiative: Strategicplan 2004–2008,2003
5. Will containment of wild poliovirus in laboratoriesand inactivated poliovirus vaccine production sitesbe effective for global certification?;Dowdle;Bull WHO,2004